Portuguese propolis: A potential source of environmentally friendly biofungicides

[Excerpt] The need to increase food production to feed an increasingly growing world population has led to an intensive use of pesticides. Globally, 4.6 million tons of chemical pesticides are sprayed into the environment every year1 . Out of the total consumption of pesticides, 17.5% are in the form of fungicides. However, pesticides have undesirable characteristics, such as the development of pathogen resistance and long degradation periods, and negative impacts on the environment, like soil and water pollution, bioaccumulation in the food chain, toxicity to non-target organisms and public health problems2 . Therefore, new environmentally friendly natural products, which are effective, safe, biodegradable and leave no harmful residues are needed. [...]The need to increase food production to feed an increasingly growing world population has led to an intensive use of pesticides. Globally, 4.6 million tons of chemical pesticides are sprayed into the environment every year1 . Out of the total consumption of pesticides, 17.5% are in the form of fungicides. However, pesticides have undesirable characteristics, such as the development of pathogen resistance and long degradation periods, and negative impacts on the environment, like soil and water pollution, bioaccumulation in the food chain, toxicity to non-target organisms and public health problems2 . Therefore, new environmentally friendly natural products, which are effective, safe, biodegradable and leave no harmful residues are needed. Propolis is a natural resinous mixture made by honeybees (particularly Apis mellifera L.) from various plant sources and processed with salivary secretions. More than 300 different compounds have been identified so far in propolis, including several bioactive compounds such as flavonoids and phenolic acids and derivatives, which are characteristic of plant secondary metabolism and are related with diverse biological properties like antimicrobial and antioxidant activities3 . In this work we evaluated the antifungal activity of ethanolic extracts (EE) from Portuguese propolis samples against phytopathogenic fungi species responsible for considerable damage in several economically important crops. Results showed that different propolis samples have different fungitoxic efficiencies but also that different species exhibit different susceptibilities. Globally, these findings suggest that propolis EE can be explored as source of biofungicides for application in a more sustainable agriculture management. In order to evaluate this propolis application, its phytotoxicity will be studied using in vitro flax plants (Linum usitatissimum L.)

Potential of Portuguese propolis as source of biofungicides

Agriculture provides livelihoods for 40% of worldwide population1 . Due to the rapid human population growth, it is estimated that global food production will need to increase by 60% to feed over 9.8 billion people by 20502 . The use of pesticides contributes to high crop yields and effective farm management3 . Globally, 4.6 million tons of chemical pesticides are sprayed into the environment every year4,5. Out of the total consumption of pesticides, 17.5% are in the form of fungicides5 . Although efficient, these chemical controls have undesirable characteristics, such as the development of pathogen resistance, environmental pollution, long degradation periods, bioaccumulation in the food chain and toxicity to non-target organisms6 . Therefore, alternative paths to the intensive use of crop protection chemicals are needed, such as the use of natural products which are effective, biodegradable and leave no harmful residues. Propolis is a natural resinous mixture made by honeybees (particularly Apis mellifera L.) from various plant sources and bee wax. Hundreds of different compounds have been identified so far in propolis, including several bioactive compounds such as flavonoids and phenolic acids and terpene derivatives, generally associated to its antibacterial, antifungal, antiviral and antioxidant activities, among others7 . Previous work showed that propolis ethanol extracts (EEs) can be explored as source of biofungicides for application in a sustainable agriculture management 8. In this study we evaluated the antifungal activity of EEs from Portuguese propolis samples against a range of phytopathogenic fungal species that affect economically important crops in Portugal. Interestingly, results showed that different propolis samples have distinct fungitoxic activities but also that different fungi species exhibit distinct susceptibilitiesFEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/201

Partial purification and characterisation of Candida nodaensis Killer toxin

Comunicação efectuada no Yeast Genetics and Molecular Biology Meeting, Seattle, 2004.Preliminary experiments showed that C. nodaensis K factor keeps its biological activity at high NaCl concentrations and is stable after incubation in a relatively broad range of temperature and pH values, whether or not in the presence of salt. The isolation of this K toxin was already achieved by a experimental protocol involving ethanol precipitation of C. nodaensis culture supernatants. Several different approaches are now in progress in order to achieve its purification and further molecular and biochemical characterisation. The identification of the cell wall receptor for this K toxin is also under study, to perform toxin purification by affinity chromatography

Essential oils encapsulated in zeolite structures as delivery systems (EODS): an overview

Essential oils (EO) obtained from plants have proven industrial applications in the manufacturing of perfumes and cosmetics, in the production and flavoring of foods and beverages, as therapeutic agents in aromatherapy, and as the active principles or excipients of medicines and pharmaceutics due to their olfactory, physical-chemical, and biological characteristics. On behalf of the new paradigm of a more natural and sustainable lifestyle, EO are rather appealing due to their physical, chemical, and physiological actions in human beings. However, EO are unstable and susceptible to degradation or loss. To tackle this aspect, the encapsulation of EO in microporous structures as zeolites is an attractive solution, since these host materials are cheap and non-toxic to biological environments. This overview provides basic information regarding essential oils, including their recognized benefits and functional properties. Current progress regarding EO encapsulation in zeolite structures is also discussed, highlighting some representative examples of essential oil delivery systems (EODS) based on zeolites for healthcare applications or aromatherapy.The authors are grateful for the national funds provided by the FCT (Foundation for Science and Technology, Portugal) under the projects UIDB/04050/2020 (CBMA) and PTDC/AAGTEC/5269/2014 (FEDER, European Fund for Regional Development)/COM PETE/POCI—Operational Competitiveness and Internationalization Programme under the project POCI-01-0145-FEDER-006958. They are grateful for the financial support provided by the Research Centers CQ/UM through UID/QUI/0686/2020 and Project BioTecNorte (operation NORTE-01-0145-FEDER-000004), supported by the Northern Portugal Regional Operational Programme (NORTE 2020) under the Portugal 2020 Partnership Agreement through the European Regional Development Fund.info:eu-repo/semantics/publishedVersio

Antimicrobial activity of fruit packages coated with nanomaterials based in metal-ions zeolites

The transport and storage of fruits is frequently compromised by microbial contaminations, especially during the delivery of these perishable foods to the public. The development of smart packages against microbial contaminations is an alternative of great interest to help controlling post-harvest diseases. The incorporation of nanomaterials, such as metal-ions zeolites with antimicrobial properties, in the semi-rigid alveolar structure for fruits transport/storage could allow the preservation of fruit with safety and quality, by inhibiting/reducing the growth of microrganisms. In this work, metal-ions zeolite nanomaterials were incorporated on the packaging material and the antibacterial activity was tested against Escherichia coli and Staphylococcus aureus. The package material exhibited good antimicrobial activity against the two bacteria (Figure 1), which are promising results for industrial application.info:eu-repo/semantics/publishedVersio

Mechanistic studies of cytotoxicity induced by a Portuguese propolis extract, using Saccharomyces cerevisiae as eukaryotic cell model

Propolis is a natural complex mixture produced by honey bees (particularly Apis mellifera L.) by collecting exudates from various plant sources. Characterized by a plethora of chemicals, propolis is generally rich in flavonoids, phenolic acids and terpene derivatives, bioactive compounds associated to it’s antimicrobial, anti-inflammatory, antimutagenic and antioxidant activities1 . Previous work had shown that the ethanol extract of a sample from the Portuguese region of Beira Alta exhibited unique dual genotoxic and antigenotoxic effects using the yeast S. cerevisiae eukaryotic model2 . In this work we prepared two ethanol extracts (EE) of propolis samples from Pereiro (P) - Beira Alta - collected in 2010 (P10.EE) and 2017 (P17.EE) to investigate the mechanisms of cytotoxicity and genotoxicity using specific S. cerevisiae mutants. While P17.EE didn’t show any toxic effect, yeast cells exposed to P10.EE showed a considerable decreased viability along time, assessed by colony-forming units. Interestingly, the oxidative stress response-defective mutant yap1 was more resistant than the wild type, suggesting that this cytotoxic effect was not mediated by oxidative stress. P.EE’s genotoxicity was also analysed by the nucleus-cytosolic translocation of NHP6A protein, considered a marker of necrosis. P10.EE induced NHP6A protein translocation to the cytoplasm, observed by fluorescence microscopy, suggesting that cytotoxicity of this extract was indeed mediated by necrosis. Although P17.EE didn’t seem to induce necrotic cell death, both extracts induced plasma membrane integrity loss, assessed by flow cytometry, using propidium iodide as marker. As recently observed for erythroleukemic cells with Brazilian propolis3 , here we present the first evidence that also Portuguese propolis have necrotic-mediated cytotoxicity in yeast cellsEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145- FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/201

Metal ion-zeolite nanomaterials for chemodynamic therapy

A new therapeutic approach called chemodynamic therapy (CDT), which can be defined as specific OH generation in cancer cells via Fenton reactions, was recently proposed.1 The advantages of CDT can be ascribed to the higher specificity, no external field penetration depth restriction, lower side effects in normal tissues, higher-level ROS generation, lack of equipment restrictions, and non-multidrug resistance, showing the promising future of CDT for clinical translation. The varied and highly controlled structural along with the chemical properties of inorganic nanomaterials, like zeolites, make them suitable for this type of CDT. Zeolites already proved to be interesting candidates for medical and healthcare applications, and also as Fenton heterogeneous catalysts for organic degradation. The aim of this study was to assess the dual activity (antibacterial and anticancer) of metal ion-zeolite nanomaterials. The prepared metal ion-zeolite nanomaterials were tested in vitro using a human skin cancer cell line, A375, and the anti-bacterial activity was evaluated against Escherichia coli, Staphylococcus aureus and MRSA. Results obtained so far suggest that metal ion-zeolite nanomaterials could be explored as antibacterial and/or anticancer agents.info:eu-repo/semantics/publishedVersio

Preliminary evaluation of zeolite-based platforms as potential dual drug delivery systems against microbial infections in the tumor microenvironment

Several zeolite-based delivery systems (ZDS) built with faujasite structure were prepared containing silver (Ag+) and 5-Fluorouracil (5-FU) as antimicrobial and antineoplastic agents, respectively. The idea behind this drug combination is an answer to the increasing evidence of colonization of tumor microenvironments by pathogenic microorganisms and their active role in tumor growth. Two ZDS with a fixed load of 5-FU and different silver loads, Ag7(5-FU).info:eu-repo/semantics/publishedVersio

Machine learning-assisted optimization of drug combinations in zeolite-based delivery systems for melanoma therapy

Two independent artificial neural network (ANN) models were used to determine the optimal drug combination of zeolite-based delivery systems (ZDS) for cancer therapy. The systems were based on the NaY zeolite using silver (Ag+) and 5-fluorouracil (5-FU) as antimicrobial and antineoplastic agents. Different ZDS samples were prepared, and their characterization indicates the successful incorporation of both pharmacologically active species without any relevant changes to the zeolite structure. Silver acts as a counterion of the negative framework, and 5-FU retains its molecular integrity. The data from the A375 cell viability assays, involving ZDS samples (solid phase), 5-FU, and Ag+ aqueous solutions (liquid phase), were used to train two independent machine learning (ML) models. Both models exhibited a high level of accuracy in predicting the experimental cell viability results, allowing the development of a novel protocol for virtual cell viability assays. The findings suggest that the incorporation of both Ag and 5-FU into the zeolite structure significantly potentiates their anticancer activity when compared to that of the liquid phase. Additionally, two optimal AgY/5-FU@Y ratios were proposed to achieve the best cell viability outcomes. The ZDS also exhibited significant efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus); the predicted combination ratio is also effective against S. aureus, underscoring the potential of this approach as a therapeutic option for cancer-associated bacterial infections.FCT - Fundação para a Ciência e a Tecnologia (UIDB/04469/2020).A.R.B. and V.I. express their gratitude to the Portuguese Foundation for Science and Technology (FCT) for providing funding through the Ph.D. Grants SFRH/BD/141058/2018 and UI/BD/152219/2021, respectively. This research work has received financial support from national funds provided by FCT/MCTES (PIDDAC) under the projects UID/QUI/0686/2020 (CQ-UM), UIDB/04469/2020 (CEB), and UIDP/50026/2020 (ICVS). Additionally, the projects of BioTecNorte (operation NORTE-01-0145-FEDER-000004 and NORTE-01-0145-FEDER-000055) are supported by the Northern Portugal Regional Operational Program (NORTE 2020) under the Portugal 2020 Partnership Agreement, cofunded by the European Regional Development Fund (ERDF). This work was also supported by the “Contrato Programa” UIDB/04050/2020 funded by national funds through the FCT I.P. The authors also thank Patrícia R. Correia for their contribution to cell viability studies

Cinnamic acid conjugates in the rescuing and repurposing of classical antimalarial drugs

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Cinnamic acids are compounds of natural origin that can be found in many different parts of a wide panoply of plants, where they play the most diverse biological roles, often in a conjugated form. For a long time, this has been driving Medicinal Chemists towards the investigation of the therapeutic potential of natural, semi-synthetic, or fully synthetic cinnamic acid conjugates. These efforts have been steadily disclosing promising drug leads, but a wide chemical space remains that deserves to be further explored. Amongst different reported approaches, the combination or conjugation of cinnamic acids with known drugs has been addressed in an attempt to produce either synergistic or multi-target action. In this connection, the present review will focus on efforts of the past decade regarding conjugation with cinnamic acids as a tool for the rescuing or the repurposing of classical antimalarial drugs, and also on future perspectives in this particular field of research.This research was funded by Fundação para a Ciência e Tecnologia (FCT), Portugal, grants UID/QUI/50006/2019, and PTDC/BTM-SAL/29786/2017.info:eu-repo/semantics/publishedVersio